Automatic coffee-making apparatus

ABSTRACT

There is described an automatic coffee-making apparatus comprising, in a casing including coffee inlet, beverage percolation outlet and spent coffee discharge outlet means, a rotor having opposite cavities diametrically bored thereinto, and pistons slidably located in said cavities, said pistons being interconnected and forming in each respective cavity an outer space open on the rotor peripheral wall and an inner annular space of cross-sectional area less than that of the outer space, and duct means for phasedly and selectively supplying hot pressurized water in said annular spaces during percolation to discharge spent coffee.

BACKGROUND OF THE INVENTION

a. The Field of the Invention

This invention is concerned with the art of coffee-making devices and,more particularly, it is concerned with a coffee-making apparatus of theautomatic type and comprising a drum supported for rotation about agenerally horizontal axis within an apparatus casing and formed withdiametrally opposed coffee-making cavities, each adapted forsequentially operating at three work stations, upon step-by-steprotation of the drum and consecutive indexing alignment with each ofsaid work stations. Said stations comprise a first station wherein agiven amount of fresh ground coffee is supplied within the cavity inalignment therewith, a second station wherein the cavity is facing acoffee screening finely perforated diaphragm and wherein pressurized hotwater is caused to pass through the ground coffee in said cavity andover the diaphragm to produce the beverage, and a third station whereatthe spent coffee is delivered from the cavity and discharged as waste.The drum is rotated step-by-step so that when any individual cavity isstanding in alignment with said first station the diametrally opposedcavity stands facing the third station.

The apparatus is complemented with motor means (generally an electricmotor) and control means to provide the desired step-by-step rotationalsequence at operator command (the apparatus can adapt for coin triggeredoperation), with water heating, pressurizing and metering means forsupplying the proper amount to be percolated at the second station(water amount adjusting means can be provided) as well as a number ofoperative subassemblies, each comprising a drum and its casing, whichcan be associated into a multi-unit apparatus for providing beverageamounts at higher rate, than is provided in one multi-unit machine.

B. The prior Art

This art is well known and worked and a large number of machines of theabove type have been widely manufactured and sold. The U.S. Pat. No.3,593,649 is fairly representative of the art and reference is hereinmade to the disclosure and drawings of such Patent for fullunderstanding of the general structure and operation of said priormachines and, more particularly, of the several corresponding devicesthereof and which, are not forming part of the present invention, willnot further described.

In said known apparatus the rotary drum (which will be termed "rotor" asthis specification proceeds and in the appended claims, the termencompassing the drum structure and the various elements arrangedtherein and rotated therewith) comprises a body supported and driven forrotation and having a peripheral wall and two generally planar parallelside faces. According to the teaching of such U.S. Pat. No. 3,592,649,the peripheral wall of the drum is cylindrical and co-axial to the axisof rotation and a part-cylindrical perforated diaphragm is secured tothe apparatus casing. An improved shape of such drum and diaphragm hasbeen taught in another U.S. Pat. No. 3,872,782, to the presentapplicant, wherein the drum peripheral wall has the geometricalconfiguration of a spherical zone having its centre in the axis ofrotation and the diaphragm is correspondingly part-spherically shaped.

The rotor of the present coffee-making apparatus can be provided with adrum having either of such configurations and therefore the expression"peripheral wall" referred to the rotor body will encompass both acylindrical and spherical zone configuration.

In the prior art machines, their rotors each comprise two physicallydivided diametrally located opposed cylindrical cavities, each open onsaid peripheral wall of the drum and wherein a piston shaped member isslidably located for urging a layer of ground coffee, during theoperation of the machine, against the perforated diaphragm at the secondwork station and then downwardly pushing the spent coffee into adischarge passage as waste.

During the operation of the prior art machines, the amount of thepressurized hot water is phasedly supplied, at the percolation secondstation, by feeding the water into the cylindrical cavity facing thediaphragm, at the rear of the piston, which presses the ground coffeeagainst the diaphragm with a force proportional to the water pressure bythe cross-sectional area of the cavity, this pressure before percolationbeing essential for properly producing the beverage. The water is thenprogressively and slowly transferred through the piston, provided withpassages of very small cross-sectional area, into the space whichcontains the compacted ground coffee, for percolation.

Further, the delivering of the spent coffee as waste is performed at thethird station by supplying a further amount of hot pressurized water atthe rear of the piston in the cavity which faces an outlet formed in thecasing and connected to a duct to waste outlet. Said further amount ofwater is of the volume defined by the cross-sectional area of thepiston, that is, of the cavity, by the stroke of said piston.

Now, according to the essential features of the invention, there havebeen found that:

a. while the preliminary pressing and compacting of the layer of theground coffee between the piston and the perforated diaphragm at thesecond work station is essential, the percolating hot water cannotproperly and uniformly find its way through such compacted layer forproperly impregnating same and wetting each coffee particle. Further,the coffee swells when impregnated and the percolation becomes moredifficult and uneven. A beverage of a great deal better taste can beproduced from a proportionally lesser amount of ground coffee if thepercolation will be made through a coffee layer subjected to a pressurefar less than that necessary for preliminarily compacting of coffee;

b. from the standpoint of cost of operating the apparatus, a notnegligible part is that of the energy used for heating the water. Theheat supplied to the above said further amount of hot water, made use offor downwardly driving the pistons at the third work station fordelivering of the spent coffee to waste is completely wasted too. On theother hand, not water only can be supplied into the rotor for ensuringthe proper temperature level of the unit. Therefore it would bedesirable to decrease said further amount of heated water.

It is therefore a principal object of this invention to devise andprovide a new and improved coffee-making apparatus or machine which isnot subject to the above and other limitations and capable of improvedoperation both to provide a better percolation of a tasteful beverageand with more economical operation.

SUMMARY OF THE INVENTION

Therefore, the coffee-making apparatus, according to the invention, ofthe above kind comprising a rotor having diametrically opposed cavitiesopen on its peripheral wall, is essentially and primarily characterizedby the fact that it comprises diametrically co-axial cavities connectedto each other by a bored passage of cross-sectional area less than thatof the cavities wherein the pistons are slidably arranged, by the factthat said pistons are connected for concurrent stroke motion by acomponent slidably and water-tightly located in said intermediatepassage, and by the fact that pressurized hot water supply passages areprovided into said rotor, to supply said water at the rear of saidpistons in said second and third work stations, in the annular spacesformed about said piston connecting component between the rear face ofeach piston and the face ends of said intermediate passage.

These and other objects, features and advantages of the invention willbe made apparent as this description proceeds. A preferred but notlimitative embodiment of the invention will now be detailedly describedwith reference to the accompanying drawings. In such description anddrawings there will be described and shown only the parts, componentsand assemblies which are critical for the invention and defined as so inthe appended claims, while any other structural detail and complementaldevices even if necessary for the operation of the machine will not bedescribed and shown as appertaining to the prior art and taught, interalia, in the above referred to U.S. patents disclosures.

THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a somewhat diagrammatical fragmentary view of an assemblycomprising the rotor and the casing of the apparatus of the invention,the components being illustrated partly in side elevation andprincipally in cross-sectional view taken in a plane perpendicular tothe axis of the rotor and containing the axis of the cavities;

FIG. 2 illustrates part of the casing of FIG. 1 and, diagrammatically,few components of the rotor in two different rotational positionsthereof;

FIG. 3 is a more detailed and enlarged view of the rotor, mainlyillustrated in sectional view as in FIG. 1, but having its cavities andpistons arranged in the second work station for percolation;

FIG. 4 is a fragmentary exploded view of the rotor of FIG. 3;

FIG. 5 is a cross-sectional view, taken in the plane indicated at V--Vin FIG. 4, of same rotor.

DETAILED DESCRIPTION OF THE REFERRED EMBODIMENT

Referring now to the drawings, the apparatus comprises a rotor having arotor body 10 rotatably supported and step-by-step driven (according toprior art) in a casing 12. The casing is provided with an upper inletpassage 14 connected to a funnel 16 into which a known supply devicephasedly supplies metered amounts of fresh ground coffee, in directionas indicated by arrow A, and a lower discharge passage 18 through whichthe spent coffee can be delivered in direction B as waste. The casing isfixedly secured to or is integrally formed with a side tubular extensionwherein a passage 20, provided with a finely perforated diaphragm 22 atits inlet (flush with the inner peripheral wall of the casing), isformed and leads to one or more outlets 24 wherefrom the beverage exitsas percolated.

The said supply and discharge passages 14 and 18 are coaxial andvertically or essentially vertically arranged. The axis of the tubularextension and therefore of passage 20 and diaphragm 22 intersects at 90°the common axis of said passages 14 and 18.

The rotor body 10 has a (cylindrical or part-spherical) peripheral wall26 (FIGS. 3 and 5, the part-spherical configuration being illustrated inFIG. 5) generally mating with that of the casing 12, and the perforateddiaphragm 22 is arranged to slide on said wall 26 and to fully cover theoutlet of the cavity (described below) aligned with passage 20 at thesecond work station. Said rotor body has formed thereinto two co-axialdiametrically opposed cylindrical cavities 30a and 30b wherein pistons40a and 40b are respectively slidably arranged.

As far as above described, the structure and the arrangement of partscorrespond to prior art. The operation of the apparatus comprises alsosteps common to prior art, as follows: the rotor is, step-by-step,rotated for 90° each step for sequentially aligning each cavity 30a(30b) with passage 14, with passage 20 and with passage 18. During thefirst step an amount of fresh ground coffee is supplied in direction A(FIG. 1) in the upturned cavity wherein the piston is downwardlypositioned, the cavity being in the first working station. Upon rotationof 90°, the same cavity is transferred to the second station, facing thediaphragm 22 (assuming a clockwise rotation, in the FIGURE) wherein anamount M of ground coffee (see FIG. 3) is pressed against said diaphragmby the pressurized water fed on the back of the piston. The water thenslowly passes beyond the piston, wets the coffee, percolatestherethrough, filters over the diaphragm in direction F and it exits asa beverage via passage 20 and outlet 24. Upon a further rotation of 90°,the same cavity is downwardly turned above the discharge passage 18 anda further amount of hot pressurized water is supplied on the back of thepiston for urging same in the position shown in FIG. 1 for deliveringthe spent coffee as waste.

In the new apparatus of the invention the oppositely located co-axialcavities 30a and 30b are interconnected by a co-axial intermediate boredpassage of cross-sectional area for less than that of said cavities,such as from one half to three fourth of that of cavities 30a and 30b.For simplicity, said intermediate passage is formed within a tubularpart 32 illustrated as integrally formed with the rotor body 10. Apractical structure is however shown in FIGS. 3 and 4, wherein saidpassage is formed by the inner cylindrical bore 46 (FIG. 4) of a sleeve34 secured at the middle of diametral bore which forms of said cavities.The sleeve 34 is axially secured in said diametral bore by suitablemeans, such as elastic rings 36a and 36b seated into annular grooves, aseal 38, such as an O-ring, being provided for water tight connectionbetween the diametral bore and the sleeve.

The two pistons 40a and 40b, water tightly slidable in said cavities 30aand 30b, respectively, are advantageously provided with running seals42a and 42b, respectively. This latter feature, which provide effectivepressure tightness, is made feasible upon the new arrangement of theinvention, which provide a positive action on said pistons, both attheir forward and return strokes, as will be shown below. Said pistons30a and 30b are interconnected by a co-axial cylindrical connectingcomponent 44 lengthwise water-tigthly slidable within the saidintermediate passage forming bore 46. A running seal 48 (FIG. 3) can beadvantageously provided also for providing water pressure separationbetween the cavities 30a and 30b.

Therefore, each piston separates the cylindrical cavity wherein it isslidably arranged into two spaces, that is an outer space open on therotor peripheral wall, the cross-sectional area of which is that of thebore of the cavity, and an inner and annular space defined between thesame bore, the external wall of the connecting component 44, the annularrear face 50a (or 50b) of the piston and the outwardly facing end of thesleeve 34. The annular cross-sectional area of each inner space isdefined by that of the co-axial opposite cavities forming bore minusthat of the connecting component 44, that is the said annularcross-sectional area is preferably from one half to one fourth of thatof the cavities.

The duct arrangement and the manner for phasedly supplying hotpressurized water in the cavity in the second station are basicallyconventional. For example, as rather diagrammatically shown in FIG. 5, aduct 54, connected to a source of hot pressurized water (not shown)secured to a flank portion 56 of casing 12, has a bored outlet 58slidably abutting on a side face 60 of the rotor body 10. Within saidbody 10 two passages 52a and 52b are symmetrically and obliquely bored(passage 52 is indicated in phantom lines in FIG. 5) each having itsinlet on said side face 60 and its outlet communicating with the one andrespectively the other of said annular spaces at the rear of eitherpiston (the outlet of passage 52a can be seen in FIG. 4), said inletsbeing so arranged (in known manner) so that when the cavity 30a (or thecavity 30b) is at the second percolation station (FIG. 3), the annularspace at the rear of piston 40a (or 40b) is connected with the source ofhot pressurized water.

Further, each annular space communicates with the cylindrical cavityfacing the adjacent piston by further passages bored in the adjacent endportion of connecting component 44 and in members connected to theadjacent piston, such as indicated at 68a, 70a (which is a small chokingbore for metered rate of passage), 72a and 74, the latter being formedabout the head of a tubular screw which secures the piston 40a to theadjacent end of component 44 and ensures an even spreading of the waterin front of said piston. Said arrangement is symmetrically similar inthe part adjacent to piston 40b.

The apparatus having the above features, according to the invention,operates in the advantageous manner described below:

Assuming that the rotor is in the position shown in FIG. 3, wherein thecavity 30a, which contains the amount M of fresh ground coffee, is atthe second or percolation station, the source of hot pressurized waterwill be connected (by the indexing of passages shown in FIG. 5) to theannular space at the rear of piston 40a. At first, this piston will bebiased in direction F by the pressure of the water of said annularspace, the biasing force being given by the pressure by thecross-sectional area of said annular passage, that is, of the annularstepped rear face 50a of the piston. Said force will properly compactthe coffee M against the diaphragm 22.

Then, the water will begin to slowly pass in the cavity at the front ofpiston 30a and to wet the coffee M, which will being to swell in thecavity. The compactness and the swelling of the coffee provide asubstantial resistance to percolation and therefore a counterpressure isprogressively built-up in the cavity, which provides a counter biasingforce in direction S on the piston 30a. It is to be taken into accountthat such counter force is given by the pressure build-up at the frontof piston 30a by the entire cross-sectional area of the cavity and, evenif such counter pressure is lowered by the percolation in direction F,by suitable dimensioning of (by experiments) the choking passage at 70aand the relationship between the annular and circular cross-sectionalareas, a substantial balance of the biasing forces in directions F and Scan be reached, so that the compactness of the coffee M will besubstantially decreased and the water will readily and uniformlypercolate through any part and contact any particle of coffee M.

It has been experienced that no strict criticalities exist in the abovediscussed dimensioning and relationship. The above indicated ratios canbe further modified and the choking passage 70a can be that which, inthe conventional coffee-makers of the type considered, provides thedesired slow percolation.

Another important advantage of the invention consists in the fact that apositive action can be applied to provide the return stroke of thepiston (to the position of piston 40b in FIG. 1) for positivelydelivering off the spent coffee to waste, by intermittently supplyingpressurized water on the back of the piston. The extra amount of waterfor providing such positive action (provided by intermittent alignmentof the duct with an additional supply outlet at 78 (FIG. 2, while therotor quickly rotates in direction R from the second to the thirdstation) will be of the volume of said annular space, that is asubstantial saving of hot water. Such alignment will be preferablyprovided while the cavity to be evacuated is nearly in the directionindicated at R in FIG. 2, to anticipate the ejection of the spent coffeewhich will fall in the discharge passage at 18. The brief burst ofpressurized water in the annular space is accompanied by the ejection ofhot water in front of the piston, said water being spread about by thepassage at 74a and will perfectly clean and deodorize the cavity.

It has been experienced that a machine according to the invention cansafely and perfectly hygienically perform many hundred cycles betweencleaning operations.

A further important advantage of the invention is provided by theconnection between the opposite pistons 40a and 40b, provided by theconnecting component 44. The pistons are caused to jointly displacethemselves in the cavities and any positively actuated stroke isaccompanied by a corresponding motion of the other piston. Inparticular, the positive downward action applied to the piston at thirdstation provides, together with the outward motion of the piston whichejects the spent coffee to waste, the inward motion of the oppositepiston, now being at the first station (FIG. 1) for preparing theupwardly turned cavity to receive a new amount of fresh ground coffee.Such positively actuated storkes make feasible, as indicated above, theprovision of unavoidable frictional resistance causing running seals,while in the prior machines for lowering of pistons of first station theown weight only of said pistons can be relied upon, thus preventing theuse of desirable and safe elastomeric seals and the like.

I claim:
 1. A coffee-making apparatus of the kind comprising a casingconnected to a source of hot pressurized water, a rotor supported anddriven for step-by-step rotation, said casing having a coffee inlet, abeverage percolation outlet and a spent coffee discharge outlet, saidrotor having a peripheral wall, diametrically arranged and oppositelylocated equal cavities opening on said peripheral wall and oppositelylocated pistons each slidable in one of said cavities, the casingcomprising a finely perforated diaphragm at said percolation outletfacing a cavity aligned with said outlet, said rotor being intermitentlyrotated for sequentially carrying each cavity to a first station facingsaid coffee inlet, to a second station facing said percolation outletand diaphragm, to a third station facing said discharge outlet and thenagain at the first station for cycle repetition, while the oppositecavity is concurrently carried to face said discharge outlet,wherein theimprovement comprises an intermediate passage interconnecting saidcavities and having its cross-sectional area less than that of saidcavities, an intermediate component interconnecting said pistonssealingly slidable under the action of pressurized water in saidintermediate passage, each piston dividing the cavity wherein itsealingly slides into an outer space open at said peripheral wall and aninner annular space defined by said intermediate component, a steppedrear face of the piston, the adjacent face portion of said intermediatepassage and the wall of said cavity, the said rotor comprising ductmeans having their outlet in said annular space whereby hot pressurizedwater is supplied in said space at said percolation station to bias thepiston toward said peripheral wall and compact an amount of fresh groundcoffee under a give pressure between said piston and said perforateddiaphragm, in said outer space.
 2. The apparatus claimed in claim 1,wherein each piston comprises choked passages connecting said annularspace to said outer space for progressive transfer of said hotpressurized water from the former to the latter space for wetting theground coffee, decreasing said given pressure and percolating thebeverage.
 3. The apparatus claimed in claim 2, wherein each piston has afront face forming the bottom wall of the adjacent outer space andwherein the said choked passage has an inlet formed in said intermediatecomponent facing said annular space and an outwardly radially openoutlet on said piston front face.
 4. The apparatus claimed in claim 1,wherein the said rotor comprises other duct means to connect a source ofhot pressurized water to said annular space when the cavity comprisingsaid space is about at said third station.
 5. The apparatus claimed inclaim 4, wherein said other duct means are arranged to connect saidsource to said annular space when the said rotor is rotating formovement from said second to said third station, to apply a brief burstof pressurized water in said cavity briefly before that said cavityreaches said third station.
 6. The apparatus claimed in claim 1, whereinsaid rotor comprises a rotor body having peripheral wall and a diametralbore open at its both ends on said wall and forming at either its outerportions the said opposite cavities, and a bore sleeve secured in theintermediate portion of said bore to form the said intermediate passage,said sleeve having an inner bore wherein the pistons connectingcomponent sealingly slides.
 7. The apparatus claimed in claim 6, whereinthe said connecting component comprises a cylindrical member of diametersuch to provide a clearance between its cylindrical surface and therotor body bore that an annular space of cross-sectional area from onehalf to one fourth of that of said rotor bore is formed between saidbore and said member.